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Mobility and equilibrium stability analysis of pin-jointed mechanisms with equilibrium matrix SVD

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第7期8卷 1091-1100页

作者： LU Jin-yu LUO yao-zhi LI Na Department of Civil Engineering Zhejiang University Hangzhou 310027 China

Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equilibrium stability of mechanisms according to the effects of the external loads. The first and second variations of the potential energy function of mechanisms under conservative force field are analyzed. Based on the singular value decomposition (SVD) method, a new crite- rion for the mobility and equilibrium stability of mechanisms can be concluded by analyzing the equilibrium matrix. The mobility and stability of mechanisms can be classified by unified matrix formulae. A number of examples are given to demonstrate the proposed criterion. In the end, criteria are summarized in a table.

关键词： Pin-jointed mechanisms Criteria for stability of equilibrium Criteria for mobility Potential energy function Equilibrium matrix. Singular value decomposition (SVD) method

Cyclic behavior test of a new double-arch steel gate

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第11期8卷 1731-1739页

作者： LUO yao-zhi ZHU Shi-zhe CHEN Xi Space Structures Research Center Zhejiang University Hangzhou 310027 China School of Landscape Architecture and Art Zhejiang Forestry University Hangzhou 311300 China

A new double-arch structure for the gate used as tidal barrage and sluice was adopted in Caoe River Dam in China. It was a spatial structure made up of the right arch, the invert arch, the chord, etc., and was designed to bear bilateral loads. To research the cyclic behavior of the new double-arch structure, a scale-model cyclic test was conducted. First, the test setup and test method were presented in detail, and according to the test results, the cyclic behavior and failure characteristics of this structure were discussed. Then by analyzing the test cyclic envelope curve, it was found the curve was divided into three stages: the elastic stage, the local plastic stage and the failure stage at the local yield point and structural yield point. The gate model has local yield strength and structural yield strength, with both their values being bigger than that of the designing load. Therefore, the gate is safe enough for the projects. At last, dynamic property of the gate was analyzed considering additional mass of the water. It was found that the tidal bore shock would not cause resonance vibration of the gate.

关键词： Double-arch steel gate Cyclic behavior test Cyclic envelope curve Dynamic property

Numerical analysis of a ventilated supercavity under periodic motion of the cavitator

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Journal of Hydrodynamics 2021年第6期33卷 1216-1229页

作者： Yun-hua Jiang zhi-hui Zou Jia Li yao yao Le-le Yang School of Ocean Engineering and Technology Sun Yat-sen UniversityGuangzhou 510275China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Department of Aerospace Engineering Harbin Engineering UniversityHarbin 150001China AVICJonhon Optronic Technology Co. Ltd.Luoyang 471003China

This paper presents a numerical simulation of the geometry and the pressure distribution of a ventilated supercavity at different cavitator amplitudes and periods of *** numerical method is validated by comparing with the results of a semi-empirical formula under specific *** is shown that the simulation can capture the boundary fluctuations of the ventilated supercavity and its internal pressure variations in a cavitator motion *** simulation results show that the supercavity boundary experiences wave-like deformations when the wavelength of the disturbance caused by the cavitator motion is comparable to the supercavity *** is also shown that the supercavity closure changes in form between a re-entrant jet and a twin vortex owing to the variations of the pressure difference between the outside and the inside of the supercavity near the closure *** maximum diameter of the ventilated supercavity exhibits periodic changes with a double peak in each cavitator motion cycle,caused by the corresponding changes of the difference between the internal and external *** the increase of the amplitude of motion of the cavitator,the supercavity boundary has enhanced wave-like undulations,with an increased maximum diameter,and with fluctuations in the cavitation *** the period of the cavitator motion increases,the wavelength of the disturbances caused by this motion becomes greater than the supercavity length,and so the wave-like undulations of the supercavity boundary and the maximum diameter of the supercavity gradually decrease,but the variations of the cavitation number ***,with the increase of the periods,the delay effects on the variations of the characteristics of the supercavity geometry caused by cavitator motion gradually decrease,and they practically vanish for large periods.

关键词： Ventilated supercavity geometrical and pressure characteristics cavitator motion

Regulating Ni site in NiV LDH for efficient electrocatalytic production of formate and hydrogen by glycerol electrolysis

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Rare Metals 2022年第5期41卷 1583-1594页

作者： Lin Dong Guan-Ru Chang Yi Feng Xian-zhi yao Xin-yao Yu Key Laboratory of Structure and Functional Regulation of Hybrid Materials Institutes of Physical Science and Information TechnologyAnhui UniversityMinistry of Education.Hefei 230601China School of Chemistry and Chemical Engineering Huangshan UniversityHuangshan 245041China Department of Polymer Materials and Engineering Academy of Chemical EngineeringHebei University of TechnologyTianjin 300130China Ningbo Research Institute of Ecological and Environmental Sciences Ningbo 315000China Energy Materials and Devices Key Laboratory of Anhui Province for Photoelectric Conversion Anhui UniversityHefei 230601China

Energy-saving glycerol electrolysis with lower potential than water spitting endows a promising way for the concurrent production of value-added formate and high-purity hydrogen. However, there is still lack of efficient electrocatalysts at both anode and cathode for glycerol electrolysis. Herein, we report the activation of Ni site in NiV layered double hydroxide(LDH) by electrochemical and N_(2)/H_(2) plasma regulations for boosting the activity of glycerol oxidation reaction(GOR) and hydrogen evolution reaction(HER), respectively. Specifically, boosted GOR performance with a low overpotential(1.23 V at 10 mA·cm^(-2)) and a high Faradic efficiency(94%) is demonstrated by electrochemically regulated NiV LDH(ENiV LDH) with elevated valence state of Ni site. In situ Raman spectrum reveals the generation of Ni(Ⅲ) species by electrochemical regulation, and the highly active Ni(Ⅲ)can be regenerated with the process of electrochemical oxidation. Additionally, the possible reaction pathway is speculated based on the in situ Fourier transform infrared spectroscopy(FTIR) and high-performance liquid chromatography results. The plasma-regulated NiV LDH(PNiV LDH) with lower valence state of Ni site exhibits outstanding HER activity, displaying a low overpotential of 45 m V to deliver 10 mA·cm^(-2).When employing E-NiV LDH and P-NiV LDH as anode and cathode electrocatalyst, respectively, the assembled electrolyzer merely needs 1.25 V to achieve 10 m A·cm^(-2) for simultaneous production of formate and hydrogen, demonstrating remarkable 320 mV of lower potential than water electrolysis.

关键词： Glycerol electrolysis Glycerol oxidation reaction Hydrogen evolution reaction NiV LDH Formate

A pilot scale anoxic/oxic membrane bioreactor(A/O MBR) for woolen mill dyeing wastewater treatment

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Journal of Environmental Sciences 2003年第4期15卷 449-455页

作者： ZHENG Xiang FAN yao bo WEI Yuan song Department of Water Pollution Control Technology Research Center for Eco Environmental SciencesChinese Academy of SciencesBeijing 100085China.

A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, boD 5 under 5 mg/L, turbidity lower than 0 65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, boD 5, colour, and turbidity were 92 4%, 98 4%, 74% and 98 9%, respectively. Constant flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.

关键词： activated sludge backwash constant flux dyeing wastewater treatment membrane bioreactor (MBR) woolen mill

Sliding mode tracking control for miniature unmanned helicopters

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Chinese Journal of Aeronautics 2015年第1期28卷 277-284页

作者： Xian Bin Guo Jianchuan Zhang yao Zhao bo The Institute of Robotics and Autonomous System Tianjin Key Laboratory of Process Measurement and ControlSchool of Electrical Engineering and Automation Tianjin University

A sliding mode control design for a miniature unmanned helicopter is presented. The control objective is to let the helicopter track some predefined velocity and yaw trajectories. A new sliding mode control design method is developed based on a linearized dynamic model. In order to facilitate the control design, the helicopter＇s dynamic model is divided into two subsystems,such as the longitudinal-lateral and the heading-heave subsystem. The proposed controller employs sliding mode control technique to compensate for the immeasurable flapping angles＇ dynamic effects and external disturbances. The global asymptotic stability（GAS） of the closed-loop system is proved by the Lyapunov based stability analysis. Numerical simulations demonstrate that the proposed controller can achieve superior tracking performance compared with the proportionalintegral-derivative（PID） and linear-quadratic regulator（LQR） cascaded controller in the presence of wind gust disturbances.

关键词： unmanned sliding miniature compensate quadratic cascaded subsystem disturbance facilitate linearized

Development and preliminary results of a large-pixel two-layer LaBr_(3) Compton camera prototype

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Nuclear Science and Techniques 2023年第8期34卷 100-114页

作者： Ming-Hao Dong zhi-Yang yao Yong-Shun Xiao Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

Lanthanum bromide(LaBr_(3))crystal has a high energy resolution and time resolution and has been used in Compton cameras(CCs)over the past few ***,LaBr_(3) crystal arrays are difficult to process because LaBr_(3) is easy to crack and break;thus,few LaBr_(3)-based CC prototypes have been *** this study,we designed and fabricated a large-pixel LaBr_(3) CC prototype and evaluated its performance with regard to position,energy,and angular *** used two 10×10 LaBr_(3) crystal arrays with a pixel size of 5 mm×5 mm,silicon photomultipliers(SiPMs),and corresponding decoding circuits to construct our ***,a framework based on a Voronoi diagram and a lookup table was developed for list-mode projection data *** Carlo(MC)simulations based on Geant4 and experiments were conducted to evaluate the performance of our CC *** lateral position resolution was 5 mm,and the maximum deviation in the depth direction was 2.5 and 5 mm for the scatterer and absorber,*** corresponding measured energy resolu-tions were 7.65%and 8.44%,respectively,at 511 *** experimental results of ^(137)Cs point-like sources were consistent with the MC simulation results with regard to the spatial positions and full widths at half maximum(FWHMs).The angular resolution of the fabricated prototype was approximately 6°when a point-like ^(137)Cs source was centrally placed at a distance of 5 cm from the *** proposed and investigated a large-pixel LaBr_(3) CC for the first time and verified its feasibility for use in accurate spatial positioning of radiative sources with a high angular *** proposed CC can satisfy the requirements of radiative source imaging and positioning in the nuclear industry and medical applications.

关键词： Compton camera Large pixel Gamma camera LaBr_(3)detector Prototype evaluation

Dose reconstruction with Compton camera during proton therapy via subset-driven origin ensemble and double evolutionary algorithm

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Nuclear Science and Techniques 2023年第4期34卷 135-148页

作者： zhi-Yang yao Yong-Shun Xiao Ji-Zhong Zhao Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle&Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

Compton camera-based prompt gamma(PG) imaging has been proposed for range verification during proton therapy. However, a deviation between the PG and dose distributions, as well as the difference between the reconstructed PG and exact values, limit the effectiveness of the approach in accurate range monitoring during clinical applications. The aim of the study was to realize a PG-based dose reconstruction with a Compton camera, thereby further improving the prediction accuracy of in vivo range verification and providing a novel method for beam monitoring during proton therapy. In this paper, we present an approach based on a subset-driven origin ensemble with resolution recovery and a double evolutionary algorithm to reconstruct the dose depth profile(DDP) from the gamma events obtained by a cadmium-zinc-telluride Compton camera with limited position and energy resolution. Simulations of proton pencil beams with clinical particle rate irradiating phantoms made of different materials and the CT-based thoracic phantom were used to evaluate the feasibility of the proposed method. The results show that for the monoenergetic proton pencil beam irradiating homogeneous-material box phantom,the accuracy of the reconstructed DDP was within 0.3 mm for range prediction and within 5.2% for dose prediction. In particular, for 1.6-Gy irradiation in the therapy simulation of thoracic tumors, the range deviation of the reconstructed spreadout Bragg peak was within 0.8 mm, and the relative dose deviation in the peak area was less than 7% compared to the exact values. The results demonstrate the potential and feasibility of the proposed method in future Compton-based accurate dose reconstruction and range verification during proton therapy.

关键词： Prompt gamma imaging Dose reconstruction Range verification Origin ensemble Compton camera Evolutionary algorithm

Sensitivity Analysis of the Effect of Speed and Inclination Angle on Water-Entry Slamming Pressure of the bow

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China Ocean Engineering 2020年第3期34卷 432-440页

作者： ZHANG Jian YOU Yun yao zhi HUO Fa-li Jiangsu University of Science and Technology Zhenjiang 212003China Shanghai Merchant Ship Design&Research Institute Shanghai 201203China

In this paper,a method about the water-entry slamming of a two-dimensional(2D)bow structure has been proposed based on the experimental and simulation *** to this method,the sensitivity analysis has been carried out about the effect of speed and inclination angle on the slamming pressure of the ***,a 2D ship bow experimental model was performed to obtain the slamming pressure distribution at different measuring points under different ***,numerical simulation for the water-entry slamming of this experimental model was conducted to obtain the pressure distribution on the experimental model under different working ***,the experimental results were compared with the numerical simulation results to evaluate the effect of speed and inclination angle on the slamming pressure of the *** results show that the slamming pressure is more sensitive to speed variation within the low-speed *** effect of inclination angle on the slamming pressure is more obvious in the small angle *** the inclination angle is larger than 45°,the effect is limited.

关键词： model test numerical simulation water-entry slamming rigid body